7821764521 has 4 divisors (see below), whose sum is σ = 7894865232. Its totient is φ = 7748663812.

The previous prime is 7821764501. The next prime is 7821764527. The reversal of 7821764521 is 1254671287.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 7821764521 - 2²¹ = 7819667369 is a prime.

It is a super-2 number, since 2×7821764521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7821764527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36550195 + ... + 36550408.

It is an arithmetic number, because the mean of its divisors is an integer number (1973716308).

Almost surely, 2^7821764521 is an apocalyptic number.

It is an amenable number.

7821764521 is a deficient number, since it is larger than the sum of its proper divisors (73100711).

7821764521 is a wasteful number, since it uses less digits than its factorization.

7821764521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73100710.

The product of its digits is 188160, while the sum is 43.

The square root of 7821764521 is about 88440.7401653785. The cubic root of 7821764521 is about 1985.0353523430.

The spelling of 7821764521 in words is "seven billion, eight hundred twenty-one million, seven hundred sixty-four thousand, five hundred twenty-one".